iPhone 6 backlight faint after drop

I got myself this iphone for a bit of training on the backlight related problems. Iphone was dropped badly with upper portion of screen smashed. I removed the shield and nothing seems visually out of order. Connector seems in order too.

With phone turned off I'm getting a steady 4.2V all along the line up to the filter and pin2. When phone is turned on, at filter TP I get a steady 14,7V wich seems a bit too much on the low side and might explain the low backlight. Should I turn my attention to U1503 and try replacing it or there are other possible components to be checked and I'm missing right now ?